The simple solution is to move the disposal cost to the producer. Instead of the consumer paying taxes to dispose of the product, the producer must pay and now a producer which produces less waste can sell cheaper products.
Imho it didn't help all that much. I did not find numbers for the reduction in packaging, but my impresssion is "none". As for recycling the waste they collect, there are numbers between "half is just icinerated" and "only 5% is recycled": https://de.m.wikipedia.org/wiki/Duales_System_(Abfallwirtsch...